The present disclosure relates generally to a power control system and, more specifically, to a control system for an active power converter interfacing an energy source (e.g., photovoltaic generator or wind turbine), load (motor drive for elevator) or storage system (e.g. battery), connected to a power grid.
Three-phase grid-connected power electronics converters are widely applied on areas such as regenerative drives, energy storage connected to the grid, and renewable generation and transportation. When the converters are connected to weak electrical grids, the grid impedance interacts with the local control. This may results in an otherwise stable controller becoming unstable (or having low stability margins) when installed on end-user facilities. The grid impedance of end-user facilities is typically unknown at the time of installation, which may require the installer to have advanced technical knowledge, and/or result in a delayed commissioning process.
Self-commissioning techniques for power electronic converters can be used to handle uncertainty of model parameters. For three-phase converters, techniques may assume a fixed motor model and control strategy. Techniques may also apply perturbations on several frequencies.
However, only a few self-commissioning techniques have been reported for grid-side converters. The reported techniques applied to grid-connected converters are complex and oriented to particular control strategies such as deadbeat control and state-space adaptive control. The existing self-commissioning techniques typically require injection of a perturbation(s) at multiple frequencies to identify the dynamic characteristics of the electrical grid.